First, let's congratulate your friend on having a varied syllable count for the various parts of the name. My primary concern is the initials which spell BEAH which I don't believe is an actual word but could be pronounceable (Leah and Beah?). Let's take apart it's popularity. Blake peaked in the 80s. Ethan is very on trend now; too much so perhaps. Alexander has been common for decades. If she doesn't mind weathering the storm of past fashions wish them the best on their upcoming son. Good luck!